(Business 2.0) – It's tough persuading consumers to buy a huge vat of mouthwash, especially when the bottle in question holds 2.1 liters of a product best known for its unpleasant taste. Last year, however, after Pfizer introduced a redesigned club-store-size bottle of Listerine, sales grew by double digits. Keith Wilmot, Pfizer's director of sales innovation, credits the uptick to Metaphase Design Group, the St. Louis-based firm that created the new packaging for the product. Metaphase replaced the old whiskey-bottle-style container with a design that features a built-in hand grip and a larger cap. The result? The grip makes the bottle easier to lift, while the big mouth encourages buyers to chug straight from the container--which many clearly do. It used to take about six months for consumers to finish off jumbo bottles of mouthwash. Now they empty them more quickly--which means more frequent trips to the store to restock. "There's been an actual change in usage behavior," Wilmot says.

Metaphase-designed products look whimsical, but their curves, bumps, and grooves usually have a practical purpose. Bryce Rutter, an industrial designer with a Ph.D. in kinesiology, set out in 1991 to create a design firm that would be guided by the nuances of practical physiology. Metaphase has since grown to 26 employees, and the firm's in-house expertise spans fields as diverse as anatomy, cognition, and psychophysics. Revenues at privately held Metaphase have grown in tandem with its expanding client roster, which now includes Bayer, Dell, Kellogg, Kraft, and PepsiCo. "Metaphase was the first company that really sold the idea that design excellence is the integration of usability and aesthetics," says Jack Beduhn of San Diego's Art Institute of California.

Rutter says, "A lot of people in the design community don't believe science has any place in this business. We say you can measure anything--including good design."

That argument appeals to Metaphase's clients for a simple reason: Ergonomic design can improve sales. Consider the bottle Metaphase designed in 1998 for PepsiCo subsidiary Gatorade. Metaphase's research showed that there are basically two types of athletes: those who like to squeeze a sports drink from the bottle, and those who prefer to suck it out. To satisfy both groups, the new bottle featured a choke-hold grip and an ergonomic mouthpiece that fits the user's lips. It was easier to use, and it stood out on crowded store shelves--factors Gatorade cites to explain why sales jumped 25 percent after the bottle was introduced.

Rutter believes that the best way to find out what a product should do is by watching people use it in the real world. When Solo Cup hired Metaphase to redesign its disposable plates, the firm threw a series of picnics and photographed guests as they piled on the food. "We looked at it from a purely biomechanical standpoint," Rutter says. "How were people carrying their plates? What's the best way to hold it, given the design of the hand?" The result was the SoloGrips line of disposable plates, notable for their deep walls and indented hand grips. Solo marketing director Kim Healy says SoloGrips sales have been growing at a double-digit pace. For Shur-Line, a Wisconsin-based manufacturer of paint application products, hours spent filming professional housepainters contributed to Metaphase's design for a new line of ergonomic brushes.

Small details can make a big difference to consumers. When Solo hired Metaphase to design a new lid for carryout coffee cups, the team spent eight months scrutinizing the physiology of hot beverage consumption before settling on a new design with a drinking hole that can be opened or closed with one hand. Although the new Traveler Plus lid costs more to produce, it's now the standard coffee topper at 7-Eleven convenience stores, where company execs say the added expense is offset by increased customer satisfaction. Traveler Plus has even attracted attention within the traditional design community, earning it a place in New York's Museum of Modern Art.

Clever designs can also become the foundations for entirely new products. To feed harried commuters, Metaphase created the Drink 'n Crunch single-serving container for Kellogg. With an inner cup of cereal ringed by an outer cup of milk, the package eliminates the need for spoons, while the tapered shape lets motorists keep an eye on the road when tilting the cup back.

Metaphase is now working on improving hospital diagnostic instruments; another big project involves creating better fast-food packaging. None of this comes cheap--the firm charges anywhere from $50,000 to $2 million for a complete design contract. Though he declines to provide specifics, Rutter says Metaphase revenues have more than doubled since 2000 and project volume has increased by 60 percent--a lucrative trend that should be easy for any designer to grasp.